Add SemanticVisitor to dart2js.

pkg/compiler/lib/src/use_unused_api.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// This file use methods that aren't used by dart2js.dart, but that we wish to
 /// keep anyway. This might be general API that isn't currently in use,
 /// debugging aids, or API only used for testing (see TODO below).
 
 library dart2js.use_unused_api;
 
@@ skipping 10 matching lines @@
 import 'elements/modelx.dart' as modelx;
 import 'elements/visitor.dart' as elements_visitor;
 import 'filenames.dart' as filenames;
 import 'inferrer/concrete_types_inferrer.dart' as concrete_types_inferrer;
 import 'inferrer/type_graph_inferrer.dart' as type_graph_inferrer;
 import 'io/code_output.dart' as io;
 import 'js/js.dart' as js;
 import 'js_backend/js_backend.dart' as js_backend;
 import 'js_emitter/js_emitter.dart' as js_emitter;
 import 'js_emitter/program_builder.dart' as program_builder;
+import 'resolution/semantic_visitor.dart' as semantic_visitor;
 import 'source_file_provider.dart' as source_file_provider;
 import 'ssa/ssa.dart' as ssa;
 import 'tree/tree.dart' as tree;
 import 'universe/universe.dart' as universe;
 import 'util/util.dart' as util;
 
 import 'scanner/scannerlib.dart' show
     PartialClassElement,
     PartialFunctionElement;
 
@@ skipping 21 matching lines @@
   useSsa(null);
   useCodeBuffer(null);
   usedByTests();
   useElements(null, null, null, null, null);
   useIr(null, null, null);
   useCompiler(null);
   useTypes();
   useCodeEmitterTask(null);
   useScript(null);
   useProgramBuilder(null);
+  useSemanticVisitor();
 }
 
 useApi() {
   api.ReadStringFromUri uri;
 }
 
 void useConstant(constants.ConstantValue constant,
                  dart2jslib.ConstantSystem cs) {
   constant.isObject;
   cs.isBool(constant);
@@ skipping 202 matching lines @@
 }
 
 useScript(dart2jslib.Script script) {
   script.copyWithFile(null);
 }
 
 useProgramBuilder(program_builder.ProgramBuilder builder) {
   builder.buildMethodHackForIncrementalCompilation(null);
   builder.buildFieldsHackForIncrementalCompilation(null);
 }
+
+useSemanticVisitor() {
+  new semantic_visitor.BulkVisitor().apply(null, null);
+  new semantic_visitor.TraversalVisitor(null).apply(null, null);
+}